Job Entry Subsystem (JES),[1] aka Job Entry Subsystem 1 (JES1), was released by IBM as an integral part of OS/VS1 as an enhancement to the basic functions that users of VS1's predecessor, MFT, had.
IBM proclaimed[2] JES1 to be "the single most important addition" to the job scheduling provided by VS1.
JES1 was not popular,[4]: 5 because HASP and ASP users often had made local modifications (edits),[4]: 9 and wanted to retain their investment.
[5] JES1 permitted operators to submit batch jobs from local unit record equipment.
The printed and punched output of jobs running on OS/VS1, whether submitted locally or remotely, is handled by JES and may be routed to local devices, to the originating site or to another remote site.